Air conditioning system

Abstract

An air conditioning system has an evaporative cooler and a refrigerated cooler connected to a common duct connecting both of the coolers to a cooled space. A space thermostat senses space temperature of the cooled space and initiates cooling responsive thereto. A cooler selection control selects one of the coolers for cooling the cooled space responsive to the relative humidity and temperature of air outside the cooled space. The selection control delays starting of the refrigerated cooler a cool down period after the initiation of cooling. With the evaporative cooler employed in a system with, or in a system without, the refrigerated cooler, the evaporative fan is started a wetting period after the starting of the evaporative pump of the evaporative cooler to wet the evaporative pads. Additionally an exhaust vent opens when the evaporative fan of the evaporative cooler is operating and closes when the evaporative fan is stopped.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

None. However, applicant has filed Disclosure Document No. 061,545 on June 13, 1977, which document concerns this application; therefore, by separate paper it is respectfully requested that such document be retained.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to air conditioning systems and more particularly to efficient air conditioning systems of combined refrigerated and evaporative coolers.

(2) Description of the Prior Art

Air conditioning systems which employ evaporative coolers often experience difficulty in cooling a cooled space when the relative humidity rises above a critical level. This critical level varies depending on the temperature of outside air. At this critical level, the evaporation of water from the pads of the evaporative cooler is insufficient to provide the cooling capacity desired.

Workers in the art prior to my invention have solved this problem by connecting a refrigerated cooler to the cooled space to supplement the evaporative cooling with refrigerated cooling. However, such prior systems often required manually switching from the evaporative cooler to the refrigerated cooler when high humidity necessitated additional cooling.

Applicant was aware of the following references prior to filing this application: U.S. Pat. Nos. to Goettl, 3,182,718; Mercer, 3,747,362; Goettl, 3,859,818.

SUMMARY OF THE INVENTION

(1) New and useful function

I have greatly increased the efficiency and utility of air conditioning systems with refrigerated and evaporative coolers by inventing an automatic air conditioning system which automatically selects the proper cooler with which to cool the cooled space responsive to relative humidity and temperature of the outside air. Outside air will be understood to mean any air outside the cooled space, including but not limited to, attics, basements, walls and the like.

My invention initiates cooling responsive to the temperature within the cooled space, and automatically selects the proper evaporative or refrigerated cooler responsive to one of two alternative indicators of when the critical combined humidity-temperature value has been reached. By critical relative humidity and temperature conditions, I mean that combination of atmospheric vapor content and temperature which causes the evaporation of water from the evaporative pads to be so insufficient as to fail to lower the temperature of air from the evaporative cooler above the desired or effective cooling capacity.

The first alternative indicator is the temperature of air from the evaporative cooler which I call duct temperature. The duct temperature from the evaporative cooler at which evaporation from the evaporative cooler pads is no longer sufficient to provide the desired cooling capacity, I call the limit duct temperature. Once this temperature is reached it is desirable to switch to the refrigerated cooler. Thus, changes in temperature and relative humidity over a continuous range of comparative values affecting cooling capacity will be directly related to the duct temperature. By setting the limit duct temperature at a given value, switching may be efficiently accomplished responsive to the value of the duct temperature, and thence to the critical values of temperature and relative humidity described above.

The second alternative indicator is the result of taking the difference of the space temperature and the duct temperature, which I call a difference temperature. The critical value of the difference temperature which I call the limit difference temperature is measured in terms of the effective cooling capacity in relation to the space temperature. The desired cooling capacity described in connection with the first embodiment is the capacity provided by the evaporative cooler that will cool the cooled space down to a desired limit space temperature. However, when the space temperature of the cooled space is much in excess of the desired limit space temperature, the evaporative cooler, though not having the desired cooling capacity, may nevertheless provide effective cooling of the cooled space. Effective cooling capacity is that condition in which the air exhausted by the evaporative cooler may effectively cool the cooled space to a lower space temperature, which is above the desired space temperature.

Thus, for the first embodiment, if the space temperature were greatly in excess of the desired space temperature, and the humidity and temperature conditions of the outside air such that the evaporative cooler could not provide the desired cooling capacity, but could provide effective cooling for that particular space temperature, the refrigerated cooler would be employed in the first alternative to cool the cooled space during the time in which the evaporative cooler would be employed in the second alternative. The more efficient evaporative air conditioner should be used as often as possible. Therefore, the second embodiment, or difference temperature, may be seen to be more efficient in the use of the evaporative cooler. However, the first embodiment is simpler in design and operation.

It is well known in the art that an evaporative cooler does not achieve maximum cooling until after a lag time or cool down period. Thus, for each of the alternatives mentioned above, I prefer to delay the starting of the refrigerated cooler a cool down period after initiation of cooling in order to obtain a true or more accurate steady state reading of the duct temperature.

In addition, I have found that it is desirable to wet the pads of the evaporative air conditioner prior to turning on the evaporative fan. This allows the pads to be fully soaked such that when the evaporative fan is started all air pulled through the evaporative cooler will be pulled through wetted pads thereby insuring maximum cooling. If the fan were started simultaneously with the pump the air pulled through the evaporative cooler would be warm until the pads were wetted, thereby initially blowing warm air into the cooled space. Therefore, for evaporative coolers either in combination with the refrigerated coolers in the system described above or as an independent unit where the evaporative cooler alone is used to cool the cooled space and initiated thermostatically, the evaporative fan is delayed a wetting period after the starting of the evaporative pump.

Therefore, the cool down period or lag time necessary to allow the evaporative cooler to achieve maximum cooling will be the wetting period plus any additional period required to allow maximum cooling. In my invention the preferred sequence is to start the pump of the evaporative cooler to soak the pads, then to start the fan, and then after the evaporative cooler has reached a steady state cooling condition, to select the proper cooler.

Approximately simultaneous with the starting of the evaporative cooler fan a vent valve in an exhaust vent connecting the cooled space to outside air opens. A duct valve in the duct opens the connection of the evaporative cooler and blocks the connection of the refrigerated cooler to the cooled space.

For the first alternative, after the cool down period, if the duct temperature of air from the evaporative cooler is below the limit duct temperature, the evaporative cooler is left on and the refrigerated cooler is not started.

If the duct temperature of air from the evaporative cooler exceeds the limit duct temperature, the refrigerated cooler is started and the evaporative cooler is stopped. The exhaust valve closes and the duct valve in the duct opens the connection of the refrigerated cooler and blocks the connection of the evaporative coolers, to the cooled space.

For the second alternative, after the cool down period, if the difference temperature defined as the difference between the space temperature and the duct temperature, is above the limit difference temperature, the evaporative cooler is left on and the refrigerated cooler is not started. Approximately simultaneous with the starting of the fan, the vent valve in the exhaust vent connecting the cooled space to outside air opens. A duct valve in the duct opens the connection of the evaporative cooler and blocks the connection of the refrigerated cooler to the cooled space. When the difference temperature is lower than the limit difference temperature, the refrigerated cooler is started and evaporative cooler is stopped. The vent valve closes and the duct valve in the duct opens the connection of the refrigerated cooler and blocks the connection of the evaporative cooler to the cooled space.

A third embodiment of my invention includes an evaporative cooler connected by a duct to a cooled space. A space thermostat initiates cooling by the evaporative cooler. A delay control delays the starting of an evaporative fan of the evaporative cooler a wetting period after the starting of an evaporative pump of the evaporative cooler. This structure and method provides for greater efficiency in air conditioning systems having a single thermostatically controlled evaporative cooler.

Therefore, by providing automatic switching between the evaporative and refrigerated coolers and employing the appropriate cool down

Claims

I claim as my invention:

1. In an air conditioning system having

a. an evaporative cooler which uses outside air from outside the cooled space,

b. a refrigerated cooler,

c. a cooled space,

d. at least one duct connecting each of said coolers to the cooled space, and

e. a space thermostat providing means for sensing space temperature of said cooled space;

the improved structure comprising in combination with the above:

f. initiation means for initiating cooling when said space temperature exceeds a limit space temperature, including

g. switching means for switching between said evaporative cooler and said refrigerated cooler responsive to the effectiveness of the evaporative cooler as it responds to relative humidity of outside air and temperature of outside air.

2. The invention as defined in claim 1 further comprising:

h. an exhaust vent for venting air from said cooled space, space,

j. a vent valve in the vent being connected to said initiation means,

k. said initiation means additionally providing for

(i) opening said vent valve when an evaporative fan of evaporative cooler is operating, and

(ii) closing said vent valve when said evaporative fan is not operating.

3. The invention as defined in claim 1 further comprising:

h. an exhaust vent for venting air from said cooled space, and

j. said exhaust vent having a pressure relief vent valve therein.

4. The invention as defined in claim 1 further comprising:

h. said initiation means also providing for delaying the stopping of said evaporative cooler and the starting of said refrigerated cooler for a cool down period after each initiation of cooling.

5. The invention as defined in claim 1 further comprising:

h. said evaporative cooler including

(i) an evaporative fan, and

(ii) an evaporative pump,

j. said initiation means also providing for delaying starting of said evaporative fan a wetting period after starting of said evaporative pump.

6. The invention as defined in claim 1 further comprising:

h. said duct being a common duct interconnecting said cooled space and both of said coolers,

j. at least one duct valve providing means for blocking the connection of one of said coolers to said common duct when the other of said coolers is operating, and

k. said duct thermostat being in the connection of said evaporative cooler.

7. The invention as defined in claim 1 wherein said initiation means further comprises:

h. a selection control connected to said space thermostat,

j. a duct thermostat providing means for sensing duct temperature of air from said evaporative cooler,

k. said duct thermostat connected to said selection control, and

m. said selection control providing means for sensing a difference temperature,

n. said difference temperature being the difference between said space temperature and said duct temperature,

o. said selection control additionally providing control means for

(i) starting said evaporative cooler when said difference temperature exceeds a limit difference temperature,

(ii) stopping said evaporative cooler when said difference temperature does not exceed said limit difference temperature, and

(iii) starting said refrigerated cooler when said difference temperature does not exceed said limit difference temperature, all when said space temperature exceeds said limit space temperature, and

(iv) stopping each of said coolers when said space temperature is below said limit space temperature.

8. The invention as defined in claim 7 further comprising:

p. said evaporative cooler including

(i) an evaporative fan, and

(ii) an evaporative pump,

q. said selection control having manually controlled selector switch means for

(i) operating said evaporative fan to the exclusion of said evaporative pump and said refrigerated cooler,

(ii) operating said evaporative cooler to the exclusion of said refrigerated cooler,

(iii) operating said evaporative and refrigerated coolers alternatively with said switching means, and

(iv) operating said refrigerated cooler exclusive of said evaporative cooler,

in combination with the following electrical circuit of said selection control,

r. said electrical circuit of said selection control including

(i) electric switch means for connecting an output of said space thermostat to one of four terminals,

(ii) said terminals including a first terminal, a second terminal, a third terminal and a fourth terminal,

(iii) said first terminal being connected to a starter for said evaporative fan,

(iv) pump start means for connecting said second terminal to a starter for said evaporative pump,

(v) fan start means for connecting said starter for said evaporative fan through said starter for said evaporative pump to said pump start means,

(vi) said fan start means also providing the function of disconnecting said pump start means from said starter for said evaporative fan when electrical current is connected through said fan start means,

(vii) evaporative start means for connecting said third terminal to said pump start means,

(viii) thermal select means for connecting an electrical current from

an input of said thermal select means to

an output of said thermal select means

when said difference temperature does not exceed said limit difference temperature,

(ix) thermostat connection means for connecting an output of said space thermostat to said input of said thermal select means,

(x) evaporative start means for connecting a starter for said evaporative cooler to said output of the space thermostat,

(xi) said evaporative start means also performing the function of disconnecting said starter for said evaporative cooler from said output of said space thermostat responsive to current at said output of said thermal select means, and

(xii) refrigerated start means for connecting said output of said thermal select to a starter for said refrigerated cooler,

(xiii) refrigerated start means for connecting said output of said thermal select means to at least one starter for said refrigerated cooler,

(xiv) said refrigerated start means also providing the function of connecting said fourth terminal to said starter for said refrigerating cooler,

s. space connection means for connecting said space thermostat to space amplifier means for amplifying said space temperature,

t. duct connection means for connecting said duct thermostat to duct amplifier means for amplifying said duct temperature,

u. said space connection means and said duct connection means being such that the values of said amplified space temperature and said amplified duct temperature may be electrically altered,

v. amplifier connection means for connecting said duct amplifier means and said space amplifier means to comparature means for permitting current to flow from said input to said thermal select means to an output of said thermal select means,

w. said amplifier connection means being such that the relative values of said amplified duct temperature and said amplified space temperature may be altered,

x. refrigerated delay means interposed between said duct connection means and said duct thermostat for delaying the connection of current through said duct thermostat for a delay interval after electrical current has been connected to said refrigerated delay means, and

y. said fan start means also providing a function of delaying the starting of said evaporative fan a wetting period after electrical current is applied thereto.

9. The invention as defined in claim 1 wherein said initiation means further comprises:

h. a selection control connected to said space thermostat,

j. a duct thermostat providing means for sensing duct temperature of air from said evaporative cooler,

k. said duct thermostat being connected to said selection control,

m. said selection control providing control means for

(i) starting said evaporative cooler when said duct temperature does not exceed a limit duct temperature,

(ii) stopping said evaporative cooler when said duct temperature exceeds said limit duct temperature, and

(iii) starting said refrigerated cooler when said duct temperature exceeds said limit duct temperature,

all when said space temperature exceeds said limit space temperature, and

(iv) stopping each of said coolers when the space temperature is below said limit space temperature.

10. The invention as defined in claim 9 further comprising:

n. said evaporative cooler including

(i) an evaporative fan, and

(ii) an evaporative pump,

o. said selection control having manually controlled selector switch means for

(i) operating said evaporative fan to the exclusion of said evaporative pump and said refrigerated cooler,

(ii) operating said evaporative cooler exclusion of said refrigerated cooler,

(iii) operating said evaporative and refrigerated coolers alternatively with said switching means, and

(iv) operating said refrigerated cooler exclusive of said evaporative cooler,

in combination with an electrical circuit in said selection control,

p. said electrical circuit in said selection control including

(i) selector switch means for connecting an output side of said space thermostat to one of four terminals,

(ii) said terminals including a first terminal, a second terminal, a third terminal and a fourth terminal,

(iii) said first terminal being connected to a starter for said evaporative fan,

(iv) pump start means for connecting said second terminal to a starter for said evaporative pump,

(v) fan start means for connecting said starter for said evaporative fan through said starter for said evaporative pump to said pump start means,

(vi) said fan start means also providing the function of disconnecting said pump start means from said starter for said evaporative fan when an electrical current is connected through said fan start means,

(vii) evaporative start means for connecting said third terminal to said pump start means,

(viii) duct connection means for connecting said third terminal to an input of said duct thermostat,

(ix) duct control means for disconnecting said duct connections and evaporative connection means when an electrical current is not flowing from said third terminal,

(x) refrigerated start means for connecting said output of said duct thermostat to at least one starter for said refrigerated cooler, and

(xi) said refrigerated start means also providing the function of connecting an electrical current through said fan control means, thereby disconnecting power from said starter for said evaporative fan when an electrical current is connected to said starter for said refrigerated cooler,

q. refrigerated delay means interposed between said duct connection means and said duct thermostat for delaying the connection of current through said duct thermostat for a delay interval after electrical current has been connected to said refrigerated delay means, and

r. said fan start means also providing a function of delaying the starting of said evaporative fan a wetting period after electrical current is applied thereto.

11. The improved method for cooling a cooled space having

a. an evaporative cooler which uses air from outside the cooled space,

b. a refrigerated cooler,

c. said refrigerated and evaporative coolers being connected by a duct to said cooled space, and

d. a space thermostat providing means for sensing space temperature of the cooled space;

comprising the combined steps of:

e. initiating cooling of said cooled space responsive to the space temperature thereof,

f. setting a limit duct temperature,

g. sensing duct temperature of air from said evaporative cooler,

h. determining if the sensed duct temperature is above or below the limit duct temperature, and

j. switching between the evaporative cooler and refrigerated cooler by

(i) starting the evaporative cooler and stopping the refrigerated cooler when said duct temperature is below the limit duct temperature, and

(ii) starting the refrigerated cooler and stopping the evaporative cooler when said duct temperature exceeds said limit duct temperature.

12. The invention as defined in claim 11 further comprising:

m. delaying the switching from said evaporative cooler to said refrigerated cooler a cool down period after said initiation step, and

n. delaying starting of an evaporative fan of said evaporative cooler a wetting period after starting of an evaporative pump of said evaporative cooler.

13. The invention as defined in claim 12 further comprising:

o. opening a vent valve for venting air from said cooled space when said evaporative fan is operating, and

p. closing said vent valve when said evaporative fan is not operating,

q. blocking the connection of said refrigerated cooler to said cooled space when said refrigerated cooler is not operating and an evaporative fan is operating,

r. blocking the connection of said evaporative cooler to said cooled space when the evaporative fan of said evaporative cooler is not operating,

s. opening the connection of said refrigerated cooler to said cooled space when said refrigerated cooler is operating, and

t. opening the connection of said evaporative cooler to said cooled space when said evaporative fan is operating.

14. The improved method for cooling a cooled space having

a. an evaporative cooler which uses air from outside the cooled space,

b. a refrigerated cooler,

c. said refrigerated and evaporative coolers being connected by a duct to said cooled space, and

d. a space thermostat providing means for sensing space temperature of the cooled space;

comprising the combined steps of:

e. initiating cooling of said cooled space responsive to the space temperature thereof,

f. setting a limit difference temperature,

g. sensing duct temperature of air from said evaporative cooler,

h. comparing said duct temperature and said space temperature, thereby

j. sensing a difference temperature which is a difference result of said comparing step, and

k. determining if the sensed difference temperature is above or below the limit difference temperature, and

m. switching between the evaporative cooler and refrigerated cooler by

(i) starting said evaporative cooler and stopping said refrigerated cooler when said difference temperature is above the limit difference temperature, and

(ii) starting said refrigerated cooler and stopping said evaporative cooler when said difference temperature is below said limit difference temperature.

15. The invention as defined in claim 14 further comprising:

o. delaying the switching from said evaporative cooler to said refrigerated cooler a cool down period after said initiation step, and

p. delaying starting of an evaporative fan of said evaporative cooler a wetting period after starting of an evaporative pump of said evaporative cooler.

16. The invention as defined in claim 15 further comprising:

q. opening a vent valve for venting air from said cooled space when said evaporative fan is operating, and

r. closing said vent valve when said evaporative fan is not operating,

s. blocking the connection of said refrigerated cooler to said cooled space when said refrigerated cooler is not operating and an evaporative fan is operating,

t. blocking the connection of said evaporative cooler to said cooled space when the evaporative fan of said evaporative cooler is not operating,

u. opening the connection of said refrigerated cooler to said cooled spacen when said refrigerated cooler is operating, and

v. opening the connection of said evaporative cooler to said cooled space when said evaporative fan is operating.

17. The improved method for cooling a cooled space having

a. an evaporative cooler which uses air from outside the cooled space,

b. a refrigerated cooler,

c. said refrigerated and evaporative coolers being connected by a duct to said cooled space, and

d. a space thermostat providing means for sensing space temperature of the cooled space;

comprising the combined steps of:

e. initiating cooling of said cooled space responsive to the space temperature thereof, and

f. switching between the evaporative cooler and refrigerated cooler responsive to the effectiveness of the evaporative cooler as it responds to relative humidity of outside air and temperature of outside air.